Compression of a portion of the spinal cord or nerve root may be caused by trauma to the spine, or by a spinal disorder, for example spinal stenosis, degenerative disc disease, a bulging or herniated intervertebral disc, bone spurs, spondylosis, or spinal osteoarthritis. Surgery may be conducted upon the affected area to relieve the compression, however the problem may reoccur prior to complete healing, or due to an ongoing disease process.
Compression of nerve tissue may take place, for example, during bending, and in particular during lateral bending, where the disc annulus is damaged or weakened. During bending, the flexion side of the disc compresses and the extension side stretches. When the pressure of compression exceeds the tissue strength of the annulus, the nucleus may be extruded through the extension side, where it commonly compresses nerve tissue. This tends to occur more towards the posterior end of the vertebral column.
As an alternative to an anterior approach to the disc or other areas of the spine, a posterior approach including a foraminotomy may be performed to access the spinal cord and impinging tissue, and to relieve compression. During a foraminotomy, bone from the posterior arch of the spine over the nerve, or lamina, and possibly part of the facet joint, is removed using special cutting instruments and/or a drill. The neuroforamen may be enlarged in some cases to decompress the affected nerve portion. Additionally, portions of the disc may be removed.
Whether an anterior or posterior approach is taken, spine stability may be compromised due to the removal of supporting tissue, leaving the spine vulnerable to further damage.